diff --git a/packages/otel-clickhouse/src/index.test.ts b/packages/otel-clickhouse/src/index.test.ts
new file mode 100644
index 0000000..fd1fd2f
--- /dev/null
+++ b/packages/otel-clickhouse/src/index.test.ts
@@ -0,0 +1,288 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { SpanStatusCode, trace } from "@opentelemetry/api";
+import {
+  BasicTracerProvider,
+  InMemorySpanExporter,
+  SimpleSpanProcessor,
+} from "@opentelemetry/sdk-trace-base";
+import { instrumentClickHouse, type InstrumentClickHouseConfig } from "./index";
+
+interface MockClickHouseClient {
+  query: (params: any) => Promise<any>;
+}
+
+describe("instrumentClickHouse", () => {
+  let provider: BasicTracerProvider;
+  let exporter: InMemorySpanExporter;
+
+  beforeEach(() => {
+    exporter = new InMemorySpanExporter();
+    provider = new BasicTracerProvider({
+      spanProcessors: [new SimpleSpanProcessor(exporter)],
+    });
+    trace.setGlobalTracerProvider(provider);
+  });
+
+  afterEach(async () => {
+    await provider.shutdown();
+    exporter.reset();
+    trace.disable();
+  });
+
+  it("wraps the query method only once", () => {
+    const client = {
+      query: vi.fn(),
+    } as unknown as MockClickHouseClient;
+
+    const instrumented = instrumentClickHouse(client as any);
+
+    expect(instrumented.query).not.toBeUndefined();
+    const wrappedQuery = instrumented.query;
+
+    instrumentClickHouse(client as any);
+
+    expect(instrumented.query).toBe(wrappedQuery);
+  });
+
+  it("records a successful query", async () => {
+    const client = {
+      query: vi.fn(() =>
+        Promise.resolve({
+          response_headers: {
+            "x-clickhouse-summary": JSON.stringify({
+              read_rows: "1000",
+              read_bytes: "8192",
+              written_rows: "0",
+              written_bytes: "0",
+              total_rows_to_read: "1000",
+              result_rows: "50",
+              result_bytes: "2048",
+              elapsed_ns: "1500000",
+            }),
+          },
+        })
+      ),
+    } as unknown as MockClickHouseClient;
+
+    const instrumented = instrumentClickHouse(client as any);
+
+    await instrumented.query({ query: "SELECT * FROM users" });
+
+    const spans = exporter.getFinishedSpans();
+    expect(spans).toHaveLength(1);
+
+    const span = spans[0];
+    expect(span.name).toBe("clickhouse.select");
+    expect(span.status.code).toBe(SpanStatusCode.OK);
+    expect(span.attributes["db.system"]).toBe("clickhouse");
+    expect(span.attributes["db.operation"]).toBe("SELECT");
+    expect(span.attributes["db.statement"]).toBe("SELECT * FROM users");
+  });
+
+  it("captures execution statistics", async () => {
+    const client = {
+      query: vi.fn(() =>
+        Promise.resolve({
+          response_headers: {
+            "x-clickhouse-summary": JSON.stringify({
+              read_rows: "1000",
+              read_bytes: "8192",
+              written_rows: "0",
+              written_bytes: "0",
+              total_rows_to_read: "1000",
+              result_rows: "50",
+              result_bytes: "2048",
+              elapsed_ns: "1500000",
+            }),
+          },
+        })
+      ),
+    } as unknown as MockClickHouseClient;
+
+    const instrumented = instrumentClickHouse(client as any, {
+      captureExecutionStats: true,
+    });
+
+    await instrumented.query({ query: "SELECT * FROM users" });
+
+    const spans = exporter.getFinishedSpans();
+    expect(spans).toHaveLength(1);
+
+    const span = spans[0];
+    expect(span.attributes["clickhouse.read_rows"]).toBe(1000);
+    expect(span.attributes["clickhouse.read_bytes"]).toBe(8192);
+    expect(span.attributes["clickhouse.result_rows"]).toBe(50);
+    expect(span.attributes["clickhouse.result_bytes"]).toBe(2048);
+    expect(span.attributes["clickhouse.elapsed_ns"]).toBe(1500000);
+  });
+
+  it("records a failed query", async () => {
+    const error = new Error("Query failed");
+    const client = {
+      query: vi.fn(() => Promise.reject(error)),
+    } as unknown as MockClickHouseClient;
+
+    const instrumented = instrumentClickHouse(client as any);
+
+    await expect(
+      instrumented.query({ query: "SELECT * FROM users" })
+    ).rejects.toThrow("Query failed");
+
+    const spans = exporter.getFinishedSpans();
+    expect(spans).toHaveLength(1);
+
+    const span = spans[0];
+    expect(span.name).toBe("clickhouse.select");
+    expect(span.status.code).toBe(SpanStatusCode.ERROR);
+    expect(span.events).toHaveLength(1);
+    expect(span.events[0].name).toBe("exception");
+  });
+
+  it("respects captureQueryText option", async () => {
+    const client = {
+      query: vi.fn(() => Promise.resolve({ response_headers: {} })),
+    } as unknown as MockClickHouseClient;
+
+    const instrumented = instrumentClickHouse(client as any, {
+      captureQueryText: false,
+    });
+
+    await instrumented.query({ query: "SELECT * FROM users" });
+
+    const spans = exporter.getFinishedSpans();
+    expect(spans).toHaveLength(1);
+
+    const span = spans[0];
+    expect(span.attributes["db.statement"]).toBeUndefined();
+  });
+
+  it("truncates long queries", async () => {
+    const longQuery = "SELECT * FROM users WHERE " + "a = 1 AND ".repeat(200);
+    const client = {
+      query: vi.fn(() => Promise.resolve({ response_headers: {} })),
+    } as unknown as MockClickHouseClient;
+
+    const instrumented = instrumentClickHouse(client as any, {
+      maxQueryTextLength: 100,
+    });
+
+    await instrumented.query({ query: longQuery });
+
+    const spans = exporter.getFinishedSpans();
+    expect(spans).toHaveLength(1);
+
+    const span = spans[0];
+    const statement = span.attributes["db.statement"] as string;
+    expect(statement.length).toBeLessThanOrEqual(103); // 100 + "..."
+    expect(statement).toContain("...");
+  });
+
+  it("includes database name when configured", async () => {
+    const client = {
+      query: vi.fn(() => Promise.resolve({ response_headers: {} })),
+    } as unknown as MockClickHouseClient;
+
+    const instrumented = instrumentClickHouse(client as any, {
+      dbName: "analytics",
+    });
+
+    await instrumented.query({ query: "SELECT * FROM users" });
+
+    const spans = exporter.getFinishedSpans();
+    expect(spans).toHaveLength(1);
+
+    const span = spans[0];
+    expect(span.attributes["db.name"]).toBe("analytics");
+  });
+
+  it("includes network metadata when configured", async () => {
+    const client = {
+      query: vi.fn(() => Promise.resolve({ response_headers: {} })),
+    } as unknown as MockClickHouseClient;
+
+    const instrumented = instrumentClickHouse(client as any, {
+      peerName: "clickhouse.example.com",
+      peerPort: 8123,
+    });
+
+    await instrumented.query({ query: "SELECT * FROM users" });
+
+    const spans = exporter.getFinishedSpans();
+    expect(spans).toHaveLength(1);
+
+    const span = spans[0];
+    expect(span.attributes["net.peer.name"]).toBe("clickhouse.example.com");
+    expect(span.attributes["net.peer.port"]).toBe(8123);
+  });
+
+  it("detects different operation types", async () => {
+    const client = {
+      query: vi.fn(() => Promise.resolve({ response_headers: {} })),
+    } as unknown as MockClickHouseClient;
+
+    const instrumented = instrumentClickHouse(client as any);
+
+    await instrumented.query({ query: "INSERT INTO users VALUES (1, 'test')" });
+    await instrumented.query({ query: "UPDATE users SET name = 'test'" });
+    await instrumented.query({ query: "DELETE FROM users WHERE id = 1" });
+
+    const spans = exporter.getFinishedSpans();
+    expect(spans).toHaveLength(3);
+
+    expect(spans[0].name).toBe("clickhouse.insert");
+    expect(spans[0].attributes["db.operation"]).toBe("INSERT");
+
+    expect(spans[1].name).toBe("clickhouse.update");
+    expect(spans[1].attributes["db.operation"]).toBe("UPDATE");
+
+    expect(spans[2].name).toBe("clickhouse.delete");
+    expect(spans[2].attributes["db.operation"]).toBe("DELETE");
+  });
+
+  it("handles queries without execution stats", async () => {
+    const client = {
+      query: vi.fn(() => Promise.resolve({ response_headers: {} })),
+    } as unknown as MockClickHouseClient;
+
+    const instrumented = instrumentClickHouse(client as any, {
+      captureExecutionStats: true,
+    });
+
+    await instrumented.query({ query: "SELECT * FROM users" });
+
+    const spans = exporter.getFinishedSpans();
+    expect(spans).toHaveLength(1);
+
+    const span = spans[0];
+    expect(span.status.code).toBe(SpanStatusCode.OK);
+    // Stats should not be present
+    expect(span.attributes["clickhouse.read_rows"]).toBeUndefined();
+  });
+
+  it("skips execution stats when disabled", async () => {
+    const client = {
+      query: vi.fn(() =>
+        Promise.resolve({
+          response_headers: {
+            "x-clickhouse-summary": JSON.stringify({
+              read_rows: "1000",
+              read_bytes: "8192",
+            }),
+          },
+        })
+      ),
+    } as unknown as MockClickHouseClient;
+
+    const instrumented = instrumentClickHouse(client as any, {
+      captureExecutionStats: false,
+    });
+
+    await instrumented.query({ query: "SELECT * FROM users" });
+
+    const spans = exporter.getFinishedSpans();
+    expect(spans).toHaveLength(1);
+
+    const span = spans[0];
+    expect(span.attributes["clickhouse.read_rows"]).toBeUndefined();
+  });
+});